Signal responsive display apparatus

ABSTRACT

A light transmitting rod for carrying a flash of light from a flash source to a point adjacent a translucent scale onto which the flash is projected. The rod is rotated relative to the scale. One or more flashes may be generated during one revolution of the rod relative to the scale with such flashes representing the time relation between electrical signals which in turn may represent the boundaries or limits of a measured parameter.

United States Patent [1 1 [111 3,741,013 Hering et al. a June 26, 1973 SIGNAL RESPONSIVE DISPLAY 2,806,402 9/1957 Ferris 340/282 X P T 3,037,295 6/1962 Roberson 33/205.5 R X A PARA Us 1,912,768 6/1933 Gilbert 33/205.5 R UX [75] Inventors: Donald R. Haring; James M. 2,197,227 4/1940 Strength 33/2055 R X Lindsey, both of Houston, Tex. [7 3] Assignee: Sperry-Sun Well Surveying Primary Examiner-Jerry W. Myracle Company, Sugar L d, T Attorney-George L. Church, Donald R. Johnson, Wilmer E. McCorquodale, Jr. and John-E. Holder [22] Filed: Nov. 4, 1970 [21] Appi. No.: 86,879 [57] ABSTRACT A light transmitting rod for carrying a flash of light [52 US. Cl 73/151, 33/313, 340/282 from flash source a point adjacent a translucent 51 Int. Cl. E2lb 47/024 scale onto which the flash is p j The rod is [58] Field 01 Search 73/151; 33/205 R, tated relative to th a n r m re flashes may be 33/205 E, 312, 313; 340/318, 206, 282 generated during one revolution of the rod relative to the scale with such flashes representing the time rela- [56] References Cit d tion between electrical signals which in turn may repre- UNITED STATES PATENTS sent the boundaries or limits of a measured parameter. 2,414,916 1/1947 Yardeny et a]. 340/282 14 Claims, 3 Drawing Figures STROBE GENERATOR ,ELECTRONIC PACKAGE PAIENIEUmzs I975 TOOL FACE ONLY (IN HIGH TOOL FACE OFF SIDE AND HIGH SIDE 0 SET HIGH SIDE FIG.

STROBE GENERATOR ELECTRONIC PACKAGE F I G. 3

INVENTORS SIGNAL RESPONSIVE DISPLAY APPARATUS BACKGROUND OF THE INVENTION The present invention pertains to a display apparatus and more particularly an apparatus providing a visual display in response to electrical signals defining a parameter.

The display apparatus is disclosed herein for use with a borehole instrument. When making boreholes into the earths surface, it is often desirable for various reasons to deviate the holes from a vertical course through earth formations. The term directional drilling is applied to such operations. One example of the use of such directional drilling operations is found in the drilling of oil wells from offshore platforms. It is a common practice to build a large drilling platform which is permanently secured to the ocean floor and from which a multiplicity of wells are drilled, sometimes over 40 in number. Because of the number of wells which are drilled from a single platform, it is necessary to drill the holes laterally away from the platform so that the earth formations containing petroleum reservoirs may be penetrated at distances laterally spaced from the platform. This procedure permits production from as great an area as possible from a single platform, The economics of such a system can readily be appreciated. It is also easily understood how important the maintenance of direction and dip of such'boreholes is in order to penetrate particular formations at particular depths and thereby intersect the desired petroleum reservoirs.

A present technique for obtaining such information as to the direction of a borehole is to cease drilling and run a surveying instrument into the drill pipe on a wireline. Alternatively, the instrument may be go-deviled to the bottom of the'drill pipe. The instrument is oriented with respect to the drill stem by means of a muleshoe located in the lower end of the drill stem. The muleshoe" is simply a device for capturing the tool at the lower end of the drill stem and orienting the tool in a particular radial direction with respect to a determined point on the drill stem. For example, the drill stem normally used in such a directional drilling operation has what is termed a bent sub atits lower end which angles the lower end of the stern and thereby permits angular deviation of the drill bit. The muleshoe is normally oriented with respect to the bent sub. This in turn orients the instrument which is being positioned in the lower end of the drill stem. This series of orientation techniques-provides a correlation between the direction in which the drill bit is angled and the orientation tool. After the orientation tool is operated, generally by means of a timing mechanism, the tool is retrieved to the surface. Both of these operations are time consuming and costly, and in particular, in offshore operations where the cost of drilling is many fold that of land operations, the economies of decreasing the non-drilling time is readily appreciated. A recent development which is the subject of applicants co-pending application Ser. No. 86,877 entitled METHOD AND APPA- RATUS FOR ORIENTING A BOREHOLE DEVICE provides a means for obtaining downhole data indicative of bit orientation and transmitting such data to the surface over a single conductor cable during the drilling operation. In other systems where borehole data is transmitted to the surface, the surface read-out equipment normally includes recorders or printers for recording the data for later use. Sometimes the data is SUMMARY OF THE INVENTION With this and other objects in view, the present invention contemplates an apparatus for providing a visual display of signals representing the measured limits of a parameter. The apparatus includes a light source and light transmitting means for transmitting light from the source to a scale. The scale has indicia indicative of values of the measured parameter. Means are provided for moving the light transmitter over the scale in timed relation with a remotely located detecting device. The detecting device transmits electrical signals to the display apparatus which signals are indicative of the parameter limits.

A complete understanding of this invention may be had by reference to the following detailed description, when considered in conjunction with the accompanying drawings, illustrating embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing details of a portion of the borehole orientation instrument;

FIG. 2 is a front view depicting the face of the display apparatus for providing visual indications at the surface of parameters measured by the borehole instrument; and

FIG. 3 is a side view of such surface indicating apparatus showing the mechanism for providing such indications.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Equipment utilized in well drilling operations is well known, and is not shown in this application, since it forms no part of the invention. Such equipment is shown however in the co-pending application referred to above. The portion of a drilling apparatus which is positioned above the floor of the drilling platform includes a drill head depending from a swivel, which in turn is connected with a mud line. A bail depending from a derrick holds the upper end of the swivel in place above the platform. A goose neck connects the swivel with the mud line, which in turn is connected with a mud pump system for supplying drilling mud to the drill string which depends from the drill head. The swivel is furnished with a wireline opening boss in its upper side which enables a line wiper to be received in the upper end of the swivel. Such line wipers may be purchased from oil well drilling apparatus suppliers, and are constructed to seal off well pressure at the well head during line operations through the drill pipe. Typically such line wipers include a hydraulically actuated packing member in the interior of the wiper. The packing member is actuated by applying pressure into the A sheave is positioned on the block for passing a conductor cable into and through the line wiper. The con ductor cable is maintained on a motor driven drum which permits its play-out and take-up during the operations. The cable may be a single conductor cable having an armored covering and similar in construction to well logging cables.

A drill assembly for use in directional drilling operations may include a non-magnetic drill collar and muleshoe orienting sub. A bent sub is positioned in the drill string between the collar and a mud motor which in turn drives a rotating bit. An orienting tool is positioned within the orienting sub and is connected at its upper end with a conductor cable extending to the surface. As will be described, the orienting tool provides signals to the surface indicative of wellbore parameters. The orienting sub provides a means for establishing a predetermined orientation between the orienting tool and the bent sub which in turn is oriented with respect to the top side of the borehole.

The orienting tool houses a pendulum section, which will be described hereinafter in detail, which is used for determining the high side of the hole by means of gravity operated elements. A lamp and photocell scanning section is located in a portion of the tool adjacent the pendulum section, and provides an electrical indication of the tools orientation for transmittal to the surface. An electronic section for coding electrical signals for transmittal to the surface is included in the tool string.

Referring to FIG. 1 of the drawings, the orientating tool is shown having a pendulum section at its lower end including an outer cylindrical housing 11. The housing 11 has a threaded end portion 12 to accommodate reception of the housing within the tool 10. An 0- ring seal 14 is received within a groove about the lower end of the housing 11 and forms a seal between the housing and the interior bore of the tool housing 16. An end portion 17 extends downwardly from the housing and has a knurled outer surface to provide a convenient means for threading or screwing the pendulum section into the tool housing. A lower mounting block 18 is positioned within the lower end of the housing 11 and an upper mounting block 19 is positioned in the upper end of the same housing. Vertical holes 21 are provided through the block 19 to provide means for transmitting fluids between the upper end of the upper block 19 and the interior bore of the housing enclosed by the lower and upper blocks, 18, 19. A pendulum assembly within the housing 11 includes a central core portion 22 made of a lightweight metal. A cylindrical body 23 is positioned about the central core 22. The body 23 is made of a lightweight plastic material which has a low specific gravity permitting it to be buoyant in a fluid filling the housing. On one side of the core, the plastic material is cut away throughout a substantial portion of its length, and has a steel rod 24 positioned between spaced end portions of the plastic material. Upper and lower shaft members 26, 27 are press-fitted into the ends of the central core. The shafts 26, 27 each have ball bearings 28, 29 respectively fitted thereon. The lower ball bearing 29 is positioned in a recess in the lower block 18. The upper bearing 28 is received within a bore formed in the upper block 19. The upper shaft 26 extends upwardly through the block 19 and has a cup member 31 secured thereon by means of a set screw. The cup member has a thin peripheral wall 32 defining the outer perimeter of a hollow chamber within the cup. A slot 33 is formed in the wall of the cup and is parallel with the longitudinal axis of the shaft 26. A scanning assembly is positioned within the housing 16 above the pendulum section to form a scanning section. The cup member 31 on the pendulum assembly is shown in its cooperative arrangement with the scanning section. The scanning section includes the outer housing 16, having a synchronous motor 36 positioned in the housing near its upper end. The output of the motor is coupled to a speed reducer 37. An output shaft 38 from the speed reducer is coupled to the upper end of a scanner shaft 39 by means of coupling 41. The shaft 39 has a ball bearing 42 fitted about the shaft. The ball bearing is received within a block portion 43 positioned within the lower end of the housing 16. The bearing 42 is held in the block by retaining rings above and below the bearing. A lamp and photodetector housing 44 is positioned on the lower end of the shaft 39 and has a annular recess 46 formed on the bottom of the central portion of the housing 44 for receiving the cup shaped member 31 extending upwardly from the pendulum assembly. A cylindrical block 47 formed in the center of the recess has a lateral opening 48 sized for receiving a light sensitive device 49 such as a photocell. Appropriate passages in the block communicate with a longitudinal bore 51 in the shaft 39. The passages and bore provide a means for passage of conduction wires to electrical devices in the housing 44. The housing 44 also has a cylindrical recess 52 extending upwardly from its lower surface near one peripheral edge thereof for receiving a light source 53 such as a lamp therein. A slot 54 is formed in the wall of the cylindrical recess 52 to provide a slotted opening between the lamp and the annular recess 46. The slot is arranged so that it is opposite the lateral opening 48 in the block 47 which opening also communicates with the annular recess 46. Another slot 56 is formed in the top of the cylindrical recess 52 which corresponds in a radial position on the housing 44 with the slot 54 in the inner wall of recess 52 so that the slot 56 is on the same radial spoke as the slot 54.

A longitudinal opening 57 extends through the block portion 43 for receiving a second light sensitive device 58 such as a photocell at its lower end. The lower end of the opening 57 has a closure 59 with a slot 61 therein which is positioned radially to the central axis of the housing 44. The light sensor 58 is positioned in the longitudinal opening 57 and will be hereinafter referred to as a case reference light sensor.

A series of collector rings 62 are positioned about the shaft 39 and are held thereon by means of upper and lower collars 63, 64, positioned above and below the collector rings. The upper collar is held on the shaft by means of a set screw. The collector rings are insulated from the metal portions of the shaft. Slots 66 are formed in the wall of the hollow shaft 39 to permit passage of insulated wires from the collector rings to the photocell 49 and lamp 53 positioned in the housing 44 at the lower end of the shaft. Electrical power is supplied to the scanner assembly including the synchronous motor 36 by means of a connector 68 at the upper end of the housing which is attached to a single conductor armored cable 69. The armored wires and cable are assembled to the connector in a well known manner for providing an electrical connection between such members, and also for permitting suspension of the tool housing from the armored portion of the cable.

In the case of the present system, the synchronous motor 36 positioned within the housing 16 operates at a speed of 12,000 rpm on a 400 cycle power signal. The speed reducer 37 is arranged to provide a reduction of 100 to 1 so that for every 100 turns of the motor shaft, the shaft 38 extending from the other end of the speed reducer 37 rotates 2 revolutions per second. Thus, the scan shaft 39 and photocell 49 and lamp 53 rotate at the same rate.

The interior bore of the housing 16 below the motor 36 is filled with a fluid which not only lubricates the moving parts therein such as bearings, but also provides a dampening effect as will be described hereinafter with respect to the pendulum assembly attached to the lower end of the housing. The openings 21 are formed in the upper block 19 of the pendulum assembly and permit the fluid in the housing 16 to communicate with the interior bore of the pendulum housing 11. Preferably the fluid does not stand above the speed reducer so that the synchronous motor is not drowned by the fluid.

Referring next to FIGS. 2 and 3 of the drawings, surface equipment for providing a read-out of information from the pendulum and scan sections is shown. The read-out apparatus is comprised of a lower base portion 71 having a hollow interior 72 for receiving components of the system. A front panel 73 has a circular opening therein with a translucent plastic or glass face plate 74 placed over the circular opening. Indicia in the form of a radial scale is placed on the plate 74 by means of silk screening or the like. The scale is arcuate, and is marked off in radial degrees from 0 to 180 on both the right and left sides of the scale. Switches such as the toggle type switches shown in FIG. 2 are mounted on the front panel and provide means for operating the surface recording apparatus as will be described hereinafter. A back panel 76 extends upwardly from the base 71 of the surface recorder and has a first mounting bracket 77 thereon extending rearwardly from the panel 76. Mounting bracket 77 has an opening therein for receiving a strobe light unit 78 including a strobe lamp 81. Electrical wires 79 connect the strobe light unit with a strobe generator 82 mounted in the hollow base 72 of the apparatus. The strobe generator and light unit may be the same as those popularly used in photographic operations, and which are produced by several manufacturers. An opening is provided in the center of the back plate for receiving a bearing 83 such as a ball bearing, which in turn rotatably supports one end of a light conducting rod 84 extending through the opening. The rod 84 which may be constructed of lucite extends between the back and front panel members 76, 73 respectively and is curved along its length so that its unsupported end 85 adjacent the front panel 73 is in close proximity to the scale on the plate 74. In other words, the circular path of the rod end 85 when rotated, is approximately coincidental with the arcuate scale on plate 74. A geared pulley 86 is mounted on the rod 84 near its bearing supported end, with the pulley by the synchronous motor 88. The pulley 89 is aligned laterally with the geared pulley 86 on the lucite rod. A positive drive belt 92 extends around geared pulleys for rotating the lucite rod in response to the rotation of the synchronous motor shaft. The belt has cogs which cooperate with gear teeth on the pulleys to provide a positive no-slip movement of one pulley relative to the other. The bearing supported end of the lucite rod 84 is aligned with the center of the scale plate 74 shown in FIG. 2. The other end of the rod has an elongated flattened portion thereon aligned axially with line 94 denoting radial degrees on the outer edge of the scale.

In the downhole electrical system, signals are generated by the activation of photocells 49 and 58, and these signals are transmitted to the surface by means of the conductor cable 69. The signals may be transmitted to the surface over separate circuit paths or they may be superimposed on the power signal, thus permitting the borehole tool to operate on a single conductor cable. Such a single conductor systemis disclosed in applicants co-pending application referred to above. In any event, such signals are used to drive the strobe generator 82 at the surface. Switching means in the surface equipment permits each of the downhole signals to be displayed individually or simultaneously. For example, if the toggle switch 96 is moved to the Tool Face Only position, only signals generated by the activation of photocell 49 are passed to the strobe generator 82. If switch 97 is moved to the High Side position, only signals generated by photocell 58 are passed to the strobe generator. When these signals are received by the strobe generator, the generator is operated to provide an instantaneous flash. If switch 96 is moved to the down position marked Tool Face And High Side, both of the signals are passed to the strobe generator. In the latter mode of operation, two flashes will appear on the face of the plate 74 during each revolution of the downhole scan system and coincidentally with each synchronous revolution of the rod 84 relative to the plate 74.

The surface indicating equipment of FIGS. 2 and 3 is operative in response to the signals received from the downhole tool in the following manner. If the switches 96, 97, are activated together with the on-off switch, signals are passed from the downhole equipment to the strobe generator 82. Thereupon the strobe generator fires to momentarily light the lamp 81 on the strobe 78. Light emanating from the lamp 81 is directed onto the end of lucite rod 84 adjacent the lamp. The LUCITE rod conducts the light down the rod to its opposite end 85 where the light is directed onto the translucent plate 74. The end 85 of the rod is arranged so that light emanating therefrom in the form of a beam is opposite the scale which is placed about the periphery of plate 74. Because of the transparency of plate 74, the light beam is superimposed on the plate scale. The strobe lamp 81 is not continuously operated, but rather is activated only by the data signal derived from downhole equipment. Thus the light appearing on the scale is intermittent and coincident with data signals. The Lucite rod 84 from which the light beam is directed, is rotatable by means of the synchronous motor 88 on the surface indicator. The motor 88 is driven by the same power supply as motor 36 in the downhole scanning system, and has an equivalent speed reduction mechanism so that the Lucite rod 84 makes one revolution about the plate scale for every revolution of scan shaft 39 in the downhole scanner. Thus, if a reference correlation is made at the surface between the light beam position on the surface indicating scale and a known reference on the tool a similar correlation will exist when the tool is downhole and the orientation of such known reference can be followed at the surface. Such a technique for making this correlation will be described hereinafter with reference to the overall operation of the system.

The relation between the downhole detection and scan system relative to the surface indicator will now be described. In the downhole tool shown in FIG. 1, the weighted rod 24 in the pendulum section will seek the low or gravity side of a wellbore into which it is positioned. The pendulum is arranged to turn freely within its housing. The cup 31 which is attached by means of shaft 26 to the pendulum is free to rotate therewith. As the cup 31 rotates, a slot 33 in the wall 32 of the cup, permits light to pass therethrough. Therefore, when the scan shaft 39 turns the lamp 53 and photocell 49, the lamp and photocell periodically pass the slot 33 in cup 31 once each revolution of the shaft 39. Since the lamp and photocell are oppositely aligned, when slot 33 passes between them, the photocell 49 is activated by the lamp 53 to provide a signal. As described previously, this signal is sent to the surface indicating equipment.

In a similar manner a reference signal is generated by rotation of shaft 39 when the slot 56 in the housing 44- permits periodic light passage from the lamp 53 onto a reference or high side photocell 58. This also generates a periodic signal upon each revolution of shaft 39. Thus, upon each revolution of shaft 39 a signal is generated by each of the photocells and passed to the surface indicating equipment.

In the operation of the well tool system described herein, the following method is employed in the operation of the system. At the surface before the tool string is inserted in the drill pipe, a reference mark on the tool housing is leveled with respect to the earths surface, i.e., it is placed in an up position relative to the surface. This reference mark is in the form of a slot which cooperates with a key in the orienting sub of the drill pipe so that when the tool is lowered into the drill pipe, the reference mark assumes a predetermined position with respect to the bent sub of the drill stem. This orientation technique is set forth in detail in Applicants copending application referred to above. The portion of the tool having the reference mark (slot) extends from the portion containing the pendulum and scan section shown in FIG. 1 and may be rotated relative thereto for purposes to be described later.

Next, the surface recording equipment shown in FIGS. 2 and 3 is turned on, and the switch marked High Side is depressed to complete a circuit for providing an indication of the high side of the tool. Such indication is in the form of a flashing light which will correspond to the activation of the case reference photocell 58 in the downhole tool. This light will appear somewhere on the scale on face 74 of the surface recording instrument. Since during this calibration operation, the instrument is not being moved, the light beam should repeatedly occur at periodic intervals at the same position on the scale. The appearance of the flashing light beam will coincide with movement of the scanner housing 44 past the lamp 53 and thus passing light on to the detector photocell 58. Since the light beam moves synchronously with the scanner, the position of the light beam occurring upon closing of the high side switch will always be relative to the position of the photocell 58 which is fixed with respect to the tool housing. Thus, when the housing is aligned with respect to vertical, and the high side switch thus activated, the position of the light beam at that time on the scale is representative of the tool housing in that particular orientation.

Means (not shown or described) may be provided for desynchronizing the motor used to drive the light rod on the surface indicator. This desynchronization of the motor will cause the motor to temporarily run slower and thus cause the light flash to move with respect to the scale. This permits the light flash to be moved so that it occurs at the 0 position on the scale, and thus provides easier reading of the instrument. Since this 0 point on the scale is merely a reference point, it will readily be seen that the flash could occur at any position on the scale for ready reference; however, for the sake of simplicity and minimizing errors in the operation of the system, it would probably be better to place the high side light at the 0 position, which now corresponds to the reference mark on the tool housing being on top of the tool relative to the earths surface. Upon establishing the high side light at this position, the operator turns off the high side light. The operator then operates the switch to the Tool Face Only position. Similarly, a flashing light will appear somewhere on the face scale, this light always occurring at a position which is relative to the position of the pendulum in the tool. The operator then loosens a locking collar (not shown) which separates the portion of the tool having the reference marker (slot) from the pendulum-scan section shown in FIG. 1, and turns the upper body portion of the tool (containing the pendulum and scan assemblies), making sure that the lower portion with the reference marker is maintained in its present position, i.e., in an up position. This turning of the upper portion of the tool housing is continued until the Tool Face Only light, which is flashing now, appears at the O position on the scale. When the tool face light is in the 0 or other such reference position, the portions of the housing are once again locked together by tightening the locking collar. If the Tool Face and High Side switch on the surface indicator is now turned on, both signals occur simultaneously to provide a single light flash on the scale. The tool system is thus calibrated and ready for lowering into the drill pipe. It is noted that with less convenience, the system can be operated without utilizing the orientation procedure outlined above. For example, the position of the High Side light on the scale may be noted when the reference mark is in the up position. Then the position of the Tool Face Only" light may be noted to give the operator a picture of the relative light positions when the reference mark is in an up position, the reference mark having a predetermined positional relationship with respect to the drill. Thereafter, upon operation of the tool in the bore-hole, changes of the tool face only light from its initial position with respect to the High Side light will give the operator an indication of the direction in which the drill assembly is turned, and how many degrees of turn are involved.

In order to lower the tool into the drill pipe, the conductor cable 69 is passed over the sheave of the line block, through the line wiper and opening boss in the top of the swivel, and through the kelly. Upon emergence of the cable at the lower end of the top section, the cable is connected to the tool string at connector 68 and the assembly is pulled up into the top section. The drill pipe is held by means of slips on the platform floor. The top section is then made up with the top of the remaining pipe string, and by means of the spooling apparatus at the surface, the cable is let out, whereupon the tool is lowered into the drill string. When the tool reaches the lower end of the drill string, the portion having the reference marker slot is received within the orienting sub. A muleshoe key in the sub for receiving the orienting slot is in turn aligned with a portion of the drill, and preferably the bent sub portion of the drill, so that it is known that the key is pointing in the direction that the drill is pointing. Thus, because the High Side light is set to occur at on the indicator when the reference slot is up, the high side reading now indicates the direction the bent sub and bit is pointing.

After the tool string has seated downhole, the High Side Only switch is activated to provide a flashing light on the scale corresponding to the signals emanating from the high side photocell. Since the tool has now in all probability been rotated from its calibrating position at the surface, the high side photocell light will no longer occur at the same position, i.e., 0 position on the scale as during the calibrating operation. Again by desynchronizing the surface indicator, the flashing light may drift on the scale until it occurs on the 0 position. Again,the 0 position is only used as a convenient reference. When this is accomplished, the High Side Only switch is moved to the Tool Face And High Side switch position. At this time, two flashing lights should occur on the scale, non-simultaneously. These lights will show the angular difference on the scale representing the angular difference between the slit 61 in the housing which passes light from lamp 53 to the high side photocell 58 and the slot 33 in the cup 31 at the upper end of the. pendulum assembly, which slot 33 passes light to the tool face photocell 49. This in turn represents the angular difference between the direction which the drill is pointing as a result of its'being attached to the bent sub and the high side of the hole. This occurs because the pendulous member was set initially so that the slot 33 on the cup produces a signal from the tool face photocell 49 corresponding to the reference slot which in turn, in the hole, corresponds to the direction in which the bent sub and drill are pointing. On the surface indicator scale, this angular difference can be measured in terms of degrees to the right or left at which the bit is pointing relative to the top side of the hole. Again, this orienting step may be omitted, i.e., not desynchronizing the surface motor 88 wherein the operator may determine the direction the bit is turned by counting the number of degrees and direction the Tool Face Only" light is displaced from the High Side" light.

The drilling operator now knows which way the drill assembly must be turned in order to achieve the desired direction. Based on this information, he will continue the drilling operation, periodically taking readings from the surface indicator to determine if the corrections he is applying to the drill assembly are producingthe desired results. Means are provided in the drill stem to permit drilling fluid to bypass around the tool string while the tool string is positioned in the drill pipe. When drillinghas continued to the extent that another section or stand of drill pipe need be added to the drill string, the drilling operator will then slow the circulation of mud as much as possible, whereupon the pressure on the line wiper is released to the point that the conductor cable can be moved through the line wiper by rotating the reel at the surface. The tool is then retrieved to a position within the kelly, whereupon the tool joint between the kelly and top section of pipe is opened and another section or stand of pipe is placed in the drill string in a well known manner. Thereupon, the tool string is again lowered to the bottom of the drill string and seated in the orienting sub and the drilling operation is continued.

Although the invention described herein is shown for use with a particular borehole tool, it is readily seen that the display apparatus could have many other uses with or without borehole tools. Therefore, while particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

1. An improved visual display apparatus of the type wherein there is provided: means for generating recurring data signals; means responsive to said data signals for providing a momentary light source; and scale means spatially separated from the light source means wherein the improvement comprises: means for conducting light from said light source means to a point adjacent said scale means; and means for positioning the portion of the conducting means adjacent the scale means at a multiplicity of locations adjacent said scale means, whereby multiple light signals may be displayed on the scale means in a spatially separated manner indicative of a relationship between such signals.

2. The apparatus of claim 1 wherein said scale is translucent.

3. The apparatus of claim 1 wherein the means for generating the momentary light source is a strobe generator.

4. An apparatus for displaying multiple periodic light signals in a spatially manner indicative of a relationship between the signals, which comprises: a light source; circular translucent scale means on which to display the light signals; a rotatable light conducting member having a first end positioned adjacent said light source and a second end positioned adjacent the scale means, said member having its second end laterally displaced from its first end and the longitudinal axis of its said ends parallel; and means for .rotating said member about the longitudinal axis of its first end, thereby directing its second end at a multiplicity of locations on the scale.

5. The apparatus of claim 4 and further including means for intermittently operating said light source in response to multiple periodic electrical signals.

6. The apparatus of claim 5 wherein the rotatable light conducting member rotates in a timed relationship with the intermittent operation of the light source.

7. The apparatus of claim 6 wherein the multiple periodic electrical signals are generated in a borehole by parameter measuring means.

8. The apparatus of claim 7 wherein the means for measuring the parameters in the borehole is a periodically rotating measuring means for generating periodic electrical data and reference signals, whereby the magnitude of the measured parameters may be represented.

9. The apparatus of claim 8 wherein the periodically rotating measuring means is rotated by a first synchronous motor and wherein the means for rotating the light conducting means is a second synchronous motor operating in a timed relationship with the first synchronous motor.

10. The apparatus of claim 9 wherein said light signal generating means is a strobe generator.

1 1. An apparatus for detecting the positional attitude of an apparatus in a borehole and providing visual indications thereof at the surface, comprising: a housing arranged for positioning in a borehole; means rotatable in said housing for detecting a position in said housing having a predetermined relationship with the earths gravitational field; means attached to said detecting means for generating a periodic data signal indicative of the position of said housing; means having a predetermined fixed relationship with said housing for generating a periodic reference signal; means for transmitting said signals to the earths surface; light source means at the earth's surface responsive to said periodic data and reference signals; elongated light conducting means having one end positioned adjacent said light source means; scale means positioned adjacent the other end of said light conducting means; and means for moving said light conducting means relative to said scale means, whereby the relationship between said periodic data and reference signals may be displayed.

12. The apparatus of claim 11 and further including movable scan means in said housing for generating said first and second signals within a fixed cyclic period and wherein said moving means is operated to move said light transmitting means over said scale once during each said cyclic period.

13. The apparatus of claim 12 wherein said scan means and moving means are operated by synchronously operated motors.

14. An apparatus for visually displaying signals generated in a borehole, which comprises: downhole means for generating multiple recurring signals in a timed relationship which is indicative of the magnitude of a borehole parameter; surface means responsive to the downhole means for generating multiple recurring signals at the surface in a timed relationship with the downhole signals; scale means; means responsive to the multiple recurring signals generated at the surface for displaying recurring light signals on the scale means; and means for positioning the recurring light signals on the scale means in such a manner that the positional relationship between the recurring light signals is indicative of the timed relationship between the downhole multiple recurring signals. 

1. An improved visual display apparatus of the type wherein there is provided: means for generating recurring data signals; means responsive to said data signals for providing a momentary light source; and scale means spatially separated from the light source means wherein the improvement comprises: means for conducting light from said light source means to a point adjacent said scale means; and means for positioning the portion of the conducting means adjacent the scale means at a multiplicity of locations adjacent said scale means, whereby multiple light signals may be displayed on the scale means in a spatially separated manner indicative of a relationship between such signals.
 2. The apparatus of claim 1 wherein said scale is translucent.
 3. The apparatus of claim 1 wherein the means for generating the momentary light source is a strobe generator.
 4. An apparatus for displaying multiple periodic light signals in a spatially manner indicative of a relationship between the signals, which comprises: a light source; circular translucent scale means on which to display the light signals; a rotatable light conducting member having a first end positioned adjacent said light source and a second end positioned adjacent the scale means, said member having its second end laterally displaced frOm its first end and the longitudinal axis of its said ends parallel; and means for rotating said member about the longitudinal axis of its first end, thereby directing its second end at a multiplicity of locations on the scale.
 5. The apparatus of claim 4 and further including means for intermittently operating said light source in response to multiple periodic electrical signals.
 6. The apparatus of claim 5 wherein the rotatable light conducting member rotates in a timed relationship with the intermittent operation of the light source.
 7. The apparatus of claim 6 wherein the multiple periodic electrical signals are generated in a borehole by parameter measuring means.
 8. The apparatus of claim 7 wherein the means for measuring the parameters in the borehole is a periodically rotating measuring means for generating periodic electrical data and reference signals, whereby the magnitude of the measured parameters may be represented.
 9. The apparatus of claim 8 wherein the periodically rotating measuring means is rotated by a first synchronous motor and wherein the means for rotating the light conducting means is a second synchronous motor operating in a timed relationship with the first synchronous motor.
 10. The apparatus of claim 9 wherein said light signal generating means is a strobe generator.
 11. An apparatus for detecting the positional attitude of an apparatus in a borehole and providing visual indications thereof at the surface, comprising: a housing arranged for positioning in a borehole; means rotatable in said housing for detecting a position in said housing having a predetermined relationship with the earth''s gravitational field; means attached to said detecting means for generating a periodic data signal indicative of the position of said housing; means having a predetermined fixed relationship with said housing for generating a periodic reference signal; means for transmitting said signals to the earth''s surface; light source means at the earth''s surface responsive to said periodic data and reference signals; elongated light conducting means having one end positioned adjacent said light source means; scale means positioned adjacent the other end of said light conducting means; and means for moving said light conducting means relative to said scale means, whereby the relationship between said periodic data and reference signals may be displayed.
 12. The apparatus of claim 11 and further including movable scan means in said housing for generating said first and second signals within a fixed cyclic period and wherein said moving means is operated to move said light transmitting means over said scale once during each said cyclic period.
 13. The apparatus of claim 12 wherein said scan means and moving means are operated by synchronously operated motors.
 14. An apparatus for visually displaying signals generated in a borehole, which comprises: downhole means for generating multiple recurring signals in a timed relationship which is indicative of the magnitude of a borehole parameter; surface means responsive to the downhole means for generating multiple recurring signals at the surface in a timed relationship with the downhole signals; scale means; means responsive to the multiple recurring signals generated at the surface for displaying recurring light signals on the scale means; and means for positioning the recurring light signals on the scale means in such a manner that the positional relationship between the recurring light signals is indicative of the timed relationship between the downhole multiple recurring signals. 